Ground improvement of fill and Port Melbourne sand
The previous industrial site had been demolished, with footings removed to a depth of 1.5 m and backfilled loosely. Groundwater was at a depth of 1 m and would make removal and replacement of the loose fill difficult. A ground improvement program using High Energy Impact Compaction (HEIC) was designed and supervised by Black Geotechnical. The demolition fill, deeper fill and loose Port Melbourne Sand were mostly granular and responded well to HEIC.
Pre and post compaction testing was conducted with CPTs. A CPT comparison is shown below. It shows improvement to a depth of about 2.5 m where soft to firm clay (Unamed Recent Alluvium) is present, which does not respond to HEIC.